feat(11-01): add tags table to schema with migration and push script

- Add polymorphic tags table (entity_type/entity_id/name) with unique
  index on (entity_type, entity_id, name) and lookup index on
  (entity_type, entity_id) — pattern follows comments table (D-05/D-06/D-07)
- Add Tag/NewTag types and tagsRelations (no direct FK, query-time join)
- Hand-write src/db/migrations/0006_add_tags_table.sql following the
  established project convention (drizzle-kit generate is unusable here —
  meta/_journal.json snapshots out of sync since 0001, pre-existing since
  Phase 8) and add journal entry for 0006_add_tags_table
- Add scripts/push-11-tags-migration.ts (idempotent CREATE TABLE/INDEX IF
  NOT EXISTS) with production deploy note for manual SSH+docker exec apply

scripts/push-11-tags-migration.ts

@@ -0,0 +1,55 @@
+// PRODUCTION DEPLOY NOTE: This migration is additive-only (CREATE TABLE IF NOT EXISTS +
+// 2 indexes, no drops/truncates). Per CLAUDE.md Data Safety, apply to production via
+// SSH+docker exec BEFORE pushing Phase 11 schema-dependent code (Plans 02-04).
+// Run: npx tsx scripts/push-11-tags-migration.ts (with prod DATABASE_URL)
+import postgres from "postgres";
+
+async function push() {
+  const databaseUrl = process.env.DATABASE_URL;
+  if (!databaseUrl) {
+    console.error("DATABASE_URL environment variable is required");
+    process.exit(1);
+  }
+
+  const client = postgres(databaseUrl);
+
+  try {
+    console.log("Pushing tags table migration...");
+
+    await client`
+      CREATE TABLE IF NOT EXISTS tags (
+        id text PRIMARY KEY,
+        entity_type text NOT NULL,
+        entity_id text NOT NULL,
+        name text NOT NULL,
+        created_at timestamp with time zone DEFAULT now() NOT NULL
+      )
+    `;
+
+    await client`
+      CREATE UNIQUE INDEX IF NOT EXISTS tags_entity_name_unique
+      ON tags (entity_type, entity_id, name)
+    `;
+
+    await client`
+      CREATE INDEX IF NOT EXISTS tags_entity_idx
+      ON tags (entity_type, entity_id)
+    `;
+
+    console.log("✓ tags table created successfully");
+    process.exit(0);
+  } catch (err: unknown) {
+    if (err instanceof Error) {
+      if (err.message.includes("already exists")) {
+        console.log("✓ tags table already exists (skipped)");
+        process.exit(0);
+      }
+      console.error("Error pushing migration:", err.message);
+    } else {
+      console.error("Unknown error:", err);
+    }
+    process.exit(1);
+  }
+}
+
+push();